RSK is a merged mined sidechain that is one of the many projects that aims to help Bitcoin get smart contracts.
RSK plan is one of the few that aims to another chain that helps both the mainchain security as it shares tx fee with miners and help gain value.
It should be noted that native bitcoin based smart contract are capable with the Taproot update in a centralized to DPOS style way if one were to make it.
**If you want to learn more about RSK read it here:
**https://www.publish0x.com/icknu123/understanding-rsk-bitcoins-smart-contract-platformupdated-xzynkkj
